Experimental Housing for Montane Tiger Spiders — Poecilotheria smithi and P. subfusca: a preliminary report with comments on P. rufilata

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Experimental Housing for Poecilotheria smithi and P. subfusca [continued]

As I started thinking of the cool fog found at high elevations in Sri Lanka's mountainous south-central region, I was faced with the dilemma of recreating misty mornings and foggy afternoons without progressively dampening the cages holding my Poecilotheria smithi and P. subfusca. Also a herpetoculturist, I have worked with arboreal vipers including montane species, and currently focus on geckos of the genera Rhacodactylus and Uroplatus. I began to think about using techniques I had used to keep montane vipers and Uroplatus species in cool humid conditions and how I could incorporate them with the way I am currently keeping some Rhacodactylus. The most common species, and one that has become very popular as a "pet", is R. ciliatus, the Crested Gecko. I maintain a very large number of breeding pairs and produce hundreds of young each year. My method of housing these geckos is adapted from that used by the world's largest producer of captive bred R. ciliatus, the foundation of which is an all-screen cage. These geckos inhabit moist tropical forests, yet they do well and reproduce in dry, completely ventilated cages without supplemental heat and humidity kept from falling too low by the use of a large [10 gallon (48 l)] room humidifier. I decided that I would see if I could use this same cage and create appropriate environmental parameters for housing montane Poecilotheria.

My first concern was the screen itself. Would the tarsal claws of these tiger spiders be damaged or caught by the screen? Would the spider's movement across the screen cause any abrasion or otherwise harm them? Would the spiders be able to destroy the screen and escape? So far, with over a year in use, the screening has caused no problems.

screen cage The cage is an ESU® Reptile Fresh Air Habitat™ [www.esuweb.com; model number: 00280] measuring 18" wide x 12" deep x 20" high [46 x 30.5 x 51 cm]. All sides except for the PVC plastic floor are constructed by fine, black aluminum mesh screen framed by aluminum screen molding. A large hinged door with a latching knob is located at the front. The open ventilation of this cage would allow me to supply fog and a cool mist of air while preventing excessive accumulation of moisture.

The first step in customizing this cage for my use is to wrap plastic around the lower perimeter of the cage below the door. I use small plastic fish bags and clear packing tape to neatly create a translucent wrap that will help keep moisture in at the bottom of the cage. I then place a plastic sweater box style storage container without lid [e.g., Sterilite® #1754 15 qt.] as a tray in the bottom of the cage and fill it most of the way with substrate such as a coconut coir/vermiculite mix or soil and dry leaves. Wood lice or isopods are encouraged to live in this substrate to help breakdown decay and waste. I then place several vertical slabs of cork bark and cork bark tubes into the substrate filled tray. Vertical pieces of 2" [5 cm] dry bamboo are cut so that they wedge between the bottom and the screen at the top. A hole saw is used to create an appropriately-sized oval entrance into the bamboo. Next an elevated water dish is added. Unable to use aquarium silicone to mount plastic cups for water as I do in my vertically-oriented glass aquaria housing the other arboreal tarantulas in my collection, I attach shallow bowls using wire tied through the bark pieces. These water bowls are topped off with fresh water daily. Finally, I add a short length of silk plant for decoration. Live plants can be used instead, and certainly will contribute to naturally raising the humidity in the cage, but require direct light, which I prefer not to use with my Poecilotheria.

Once the basic cage is completed the next step is to add the environmental controls. To monitor the temperature and humidity in the cage I currently use an ESU/Coralife® mini digital thermometer [model: 00232] mounted on the outside of the cage with the external probe attached somewhere in the center of the cage both vertically and horizontally and the wire run through the door. An ESU® Humidity & Temperature Gauge™ [model: RP230] is also used and is mounted to the middle back of the cage. To create the morning fog I use ESU's Ultrasonic Terrarium Fogger™ [model: RP238], which is turned on for four hours [0500-0900] each morning by a simple household timer. The fogger is submerged in a Glad disposable food storage container filled with reverse osmosis treated water, which is set directly upon the top of the cage and covered by the inverted bottom of a large Lee's® Kritter Keeper™ [model: 20025]. Reverse osmosis water is used to minimize replacement of the fogger's transducer disc, which would be often necessary if water full of minerals and suspended solids was used. As the fogger generates its mist the vapor spills out of the water reservoir and falls downward through the top of the cage. Vapor that rises is forced downward by the Kritter Keeper™ cover, which also fills with condensation that later drips down into the cage. With several of these cages side by side the fog that moves out the sides can pass into a neighboring cage and the cool breeze surrounds the cages.

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